Question

I want to define a constant depending on the OS in use.
As such:

#include <stdio.h>

#ifdef _Win32        //Used for system("cls") command
#include <process.h>
#define CLEAR "system(\"cls\")"
#endif

#ifdef __APPLE__
#define CLEAR "system(\"clear\")"
#endif

int main()
{
   CLEAR;
}

Xcode gives me an error stating that expression result unused at
#define CLEAR "system(\"clear\") and inside the main function.

I am on a Mac.

Answer 1

Use:

#define CLEAR system("clear")

not

#define CLEAR "system(\"clear\")"

You get the error because your macro call is substituted with:

"system(\"clear\")";

which is a useless expression statement (the expression being the string here) like for example:

0;   // valid but pointless